A cobpobation of cali



Sept. 10, 1929. KQLSTER 1,727,608

' BEARING COIL HOUSING Filed Feb. 5, 1927 way I N VEN TOR.

Mam mw z 15 fla, ATTORNEY.

Patented Sept. 10, 1929.

FFEQEEL.

FREDERICK A. KOLSTER, OF PALO ALTO, CALIFORNIA, ASSIGNOR '10 FEDERAL TELE- GRAPH COMPANY, OF SAN FRANCISCO, CALIFORNIA, A. CORPORATION OF CALI- FORNIA.

BEARING-COIL HOUSING.

Application filed February 5, 1927.

My invention relates to directional radio apparatus or radio compasses for finding the bearing or direction and sense of direction of a transmitter of electro-radiant energy.

In accordance with my invention, the bearing coil of a radio system having a directional characteristic and utilized in combination with a radio system having substantially no directional characteristic to constitute a composite system by which the clirection and sense of direction of the propagation of electric energy is determined when electrical symmetry obtains between the component systems, is provided with metallic plates disposed in spaced relation thereto which aid in maintaining said electrical symmetry.

More particularly in accordance with my invention, two metallic plates disposed in spaced relation to opposite sides, specifically the upper and lower sides, of the bearing coil and in symmetrical relation with respect to the axis of rotation of said coil, are connected respectively to the mid-point of the coil and to the ground or its equivalent.

Further in accordance with my invention, the bearing coil is shielded from the mechanical effects of atmospheric disturbances by a housing within which the coil rotates, and from certain electrical effects due to the unavoidable proximity of conductors, such as stay wires, metallic superstructures and the like, by electrical connections from one metallic end plate or cap of the housing to the mid-point of the bearing coil and from the other plate or cap to the ground or its equivalent.

Furtier in accordance with my invention 40 the aforesaid housing or enclosing structure for the bearing coil comprises two metal end caps which may be castings of brass, aluminum or other suitable metal, between which is disposed a casing of suitable, rigid material, as fabric impregnated with a phenol condensation product.

My invention further resides in apparatus and structure of the character hereinafter described and claimed.

For an illustration of a form which my in- Serial No. 166,130.

vention may take, reference is to be had to the accompanying drawing, in which:

Fig. 1 is an elevational view in section of the apparatus constructed in accordance with my invention.

Fig. 2 is the schematic wiring diagram of a directional radio system including my invention.

Referring to Fig. 1, upon the surface R, preferably the roof of a ships pilot-house, is disposed the housing member or tube 1, of metal, one end of which terminates in a flange 2 suitably secured to the roof R by bolts 3 or other suitable fastening means. At its other or upper end, as viewed in Fig. 1, member 1 terminates in a threaded portion which screws into a hollow cone-shaped member 4. This member may be preferably a brass or aluminum casting and is formed with an upstanding peripheral flange which receives the lower end of the casing member 5, formed of a rigid insulating material, such as fabric impregnated with a phenol condensation product. The upper end of the member 5 is received in the flange of a cap or roof member 6, similar in composition to the base or cap member 4. The cap members and the casing disposed between them may be secured rigidly together in any suitable manner, such as by passing bolts or rivets 7 through the easing into the flanges. The lower cap member is provided with a plurality of bosses or abutments 8 having apertures therethrough to receive bolts forming the upper terminal of bracing rods or stanchions 9, connected at their lower ends to the roof B through the plates 10.

By preferance the length of the stanchions 9 and the tube 1 is such that the distance from the roof to the lowermost portion of the cap 4 is approximately 7 feet, so that a person of ordinary height may readily pass, while erect, beneath the bearing coil and its enclosing structure. Obviously, the dimensions and shape of the end caps 4 and 6 and the casing 5 should be so selected as to house or enclose the particular bearing coil used. In the example shown, coil 11 is substantially square while the casing 5 is circular in cross section and the end caps are substantially conical.

The frame members 12, upon which the coil 11 is wound, are suitably secured to a hollow shaft 13, which extends downwardly through the cap member 4:, within which is mounted the ball-bearing structure 14:, thence through the roof R to the interior of the pilothouse. The terminals of the coil 11 are connected by means of conductors, not shown, extending through the hollow shaft 18 to slip rings, not shown, within the housing 14-, upon which bear brushes to include the compass coil in a circuit hereinafter described.

Upon the floor 15, as of the ships pilothouse, is disposed the housing or hollow pedestal 16, on whose upper end is carried a ships compass 17 having a compass card. The compass may be of the magnetic type, or it may be of the repeater type controlled by a gyroscopic master compass, or the card may alone be carried upon the housing either in fixed or movable relation thereto, as a dumb compass card.

Surmounting the housing is. an annular member 18 from which arms or supports joined to a hub 19 forming a bearing for a stub shaft upon whose lower end is secured the bracket 20 having downwardly extending arms by which are carried sighting wires 21, 2:2 disposed one vertically above the other and cooperating with the scale or compass card. Dispersed within the housing 23 is mechanism associated with the lower end of shaft 13 and the stub shaft connected to the bracket 20 for correction of wave front distortion. This portion of the apparatus does not form part of this invention and may be of the type disclosed and claimed in my copending application Serial Number 34-314.

Due to the provision of the protecting structure and the mode of supporting the same independently of the bearing coil 11 and its rotating shaft 13, the load or pressure efi'ect of the wind or air currents on said coil is substantially reduced. As a result, the frictional resistance to turning movement of shaft 9, particularly at the bearing 14, is substantially diminished, and, therefore, the operator may easily and delicately rotate the aforesaid rotatable structure as is necessary in the determination of a direction or sense of direction of a radio beacon or other source of electro-radiant energy.

The metal end caps i and 6 are incorporated in the electrical system of the radio compass by connecting the upper or roof member 6 to the electrical mid-point of the bearingcoil and by connecting the lower or base member l to the ground or its equivalent for purposes more fully hereinafter described.

In Fig. 1 the loop or bearing coil of one or more turns may rotate an indicator cooperating with a direction scale, such as the card of a magnetic, gyroscopic or other com pass, or the card of a dumb compass.

The coil 11 is tuned to the frequency of the received energy by means of the variable condenser C and with it constitutes the closed circuit of the direction-iinding system.

Connected in shunt to the condenser C is an inductance or coil L whose terminals are connected respectively to the grids g and g of the thermionic amplifiers V and V The filaments, or cathodes and f are connected in parallel with each other across the terminals of a source of current or battery A for rendering the cathode electron-emissive. The anodes a and a are connected to the 0pposit-e ends of a coil comprising the split windings L L and having a mid-point 7c.

Coupled to the coil L L is the secondary S shunted by the variable tuning condenser C to whose terminals is connected the input of an amplifier and conductor system H, of any suitable type for transmitting the desired signal to the telephone or other indicating instrument T.

In the common leads between the cathodes I and f and the mid-point 7c of the coil L if is included a coil K in inductive relation to the aforesaid coil L.

The degree of coupling between the coils L and K may be varied by changing their relative position, and the coupling between them, therefore, will be understood as preferably variable, though it may be fixed when suitable or desirable. in the circuit of the coil K is the switch .9 which, on engaging the contact 15, brings the coil K into circuit with the aforesaid common lead and when in engagement with the Contact 16 cuts out of circuit the coil K.

Contact Z) is adjustable along a contact with the inductance L and is connected to the cathodes f, f through tne switch 8, when closed, or through the resistance or impedance coil F when the switch 8 is open.

From a point below or beyond the imped ance F, and from the cathodes f, f is made a connection to the lower cap member lof the housing, which is connected to the earth or its equivalent E or the housing and point and may be individually grounded.

The closed circuit, comprising the bearing coil 11 and the condenser C, constitutes a component system having a directional characteristic because of the rotatable loop or coil; and a second system, in effect an open antenna system, having substantially no directional characteristic, is comprised by the closed circuit system and the roof or cap member 6 connected to the midpoint of the loop, as a capacity area, and the connection to the earth or equivalent E, through the contact Z), impedance F or switch 8.

The presence of the end caps i and 6, one of which is connected to theelectrical mid-point of the closed circuit having a directional characteristic and the other of which is connected to the earth E or its equivalent, as has been heretofore described, minimizes the effect due to the presence of nearby conductors or metallic masses and substantially prevents them from affecting the symmetry of the closed circuit with respect to the open antenna system. The loop to ground capacity, after installation of the apparatus remains constant, and is not affected by objects below the loop since by grounding the metal cap 4,

' the earth or ground in effect, is brought in proximity to the loop. Inv other words the electrostatic field has been so restricted as to exclude objects normally in it.

The upper or roof cap member 6 prevents objects or conductors above the loop from affecting the symmetry of the system since it restricts the field of the coil in that direction. Any disturbing influence affecting the cap member, will by virtue of the midpoint con nection to the bearing coil 11, be balanced out so that it in no way affects the directional characteristics of the system.

In actual practice, the capacity of the open antenna path from loop to ground is usually supplemented by anantenna or capacity screen connected to the mid-point of the loop. In my invention, the necessity of such a structurally independent auxiliary aerial is obviated, by reason of the mid-point connection to the cap member 6.

The operation is as follows:

For determining the bearing or direction merely, as distinguished from sense of direction, of a distant transmitter or radio beacon, the switch 8 is closed, thereby short-circuiting or rendering inoperative the impedance F, and the switch 8 is thrown onto contact 16, cutting out coil K. The closed circuit is attuned to the frequency of the energy whose direction of propagation is to be-determined by suitably adjusting the condenser C; and the contact I) is moved along the balancing inductance L to position of sharp electrical symmetry of the closed circuit with respect to the earth connection or open antenna path. The plates 4 and 6 aid in maintaining this balanced or symmetrical condition for all positions of the loop as it is rotated about its axis. The coil 11 is rotated to position in which a critical response is obtained in the telephone T; generally and preferably to position where the plane of the coil 11 is normal to the bearing or direction of the distant beacon or source, in which case zero or minimum response is obtained in the telephone T, such zero or minimum response being more sharply determinable than is a maximum response in telephone T obtainable when the plane of the coil 11 coincides with the bearing or direction.

Having so determined the hearing or direction of the beason or distant source, the

sense of hearing or direction thereof is ob tained by giving the composite system, comprising the closed circuit and open antenna systems, a uni-lateral or a uni-directional characteristic without, however, disturbing the symmetry between the directional and non-directional systems previously obtained. Without moving the contact 7) from the position determining symmetry of the closed circuit with respect to the open antenna path, the switch 3 is opened, thereby inserting the impedance F in the earth connection; and the switch 8 is thrown onto contact 15, thereby bringing the coupling coil K into circuit in the common anode circuit lead of the amplifiers V and V WVith this condition of the circuits the operator then rotates the coil 11, preferably from a position in which its plane is parallel to the bearing or direction of the distant beacon or source, and the sense of change of the magnitude of the signal in the telephone T is noted. By construction or suitable predetermination, decrease of signal under these circumstances will indicate that the distant beacon or source lies to the one side of the coil 11, while, if the signal in creases, it lies to the opposite side of the rotatable coil.

With the closed circuit system electrically symmetrical with respect to the earth con nection I), E, the potentials of the grids g and g are affected in opposite senses by the high frequency received energy in the closed or loop circuit only; that is, one of the grids is positive when the other is negative, causing changes of current in the coils L and If in opposite senses, but since they are differentially coupled to the secondary S a signal is pro duced in the telephone T, enabling the operator by exploring rotation of the coil 11 to find the bearing either when the signal in the telephone T is a maximum or a minimum. There fore, as regards received energy in the loop or closed circuit system only, the two audions V and V are affected substantially equally and oppositely, without variation of anode circuit current, however, in the common B battery lead from the cathodes f, f to the point between the coils L and L Therefore, as regards received energy in the loop or closed circuit only, with switch 3 upon contact 1, there is no change of magnitude of high frequency current in the coil K, and in consequence there is no feed back or regenerative action effected by the back coupling KL from the open antenna path into the loop or closed circuit.

On the other hand, received energy existing only in the antenna path operates upon the two audions V and V in effect in parallel; that is, both grids g and g are positive or negative simultaneously, resulting in a differential effect in the coils L and L accompanied by a current variation in the common B battery lead, and, therefore, in the coupling coil K, which accordingly induces into the loop or closed circuit system an amplie fied current representative of the received energy in the open antenna path. The amplification of the open antenna current is not due to regenerative action, but is dependent only upon the simple amplifying action of the tubes V and V The current so induced by the coil K into the loop or closed circuit by its inductive effect upon the coil L, cooperates either cumulatively or differentially with the received energy directly absorbed in the loop or closed circuit, and the two energies in cooperation produce more or less perfectly a cardioid or uni-directional or uni-lateral characteristic for determining sense of bearing of a distant station or beacon.

In consequence the sense of direction or bearing may be determined by virtue of the fact that received'energy in one of the compo nent systems is transferred to the other without disturbing symmetry of the one system with respect to the other; and more particularly, the transfer of energy is accompanied by its amplification, without, however, causing regenerative or feed back action as regards the audion system.

Ordinarily, as regards the received energy in the open or antenna path, the difference of potential between the point 6 and either terminal of the inductor L is small, with corre sponding small difference of potential between the grids g, (7 and their associated cathodes f and 7. To procure a greater difference of potential the impedance F, either a resistance, or an inductance or choke coil, is utilized when the sense of direction is determined, for which purpose the audions V and V are in a sense affected in parallel or similarly by the received energy in the existing field in the open antenna path.

By a system of the character described, unidirectional operation, that is, the determination of sense of direction or hearing, is possible without destroying or need to destroy the electrical symmetry previously existing between the two conrponent systems in determining bearing or direction merely. Furthermore, the received energy in one of the systems alone, for example that'in the open antenna system, is impressed upon the other or closed circuit system or loop after amplification. And aside from the degree of amilification of the energy of the one system impressed upon the other, the degree of coupling between the two systems, as affected, for example, by the coils K, L, may be regulated or varied at will.

/Vhile separate and distinct audions V and V are indicated in the drawing, it will be understood that the anodes, grids and cathode structure may all be included within the same bulb or evacuated vessel.

Nhat I claim is:

1. The combination of a bearing coil having a natural capacity to the ground or its equivalent, and means to increase said capacity including an element of a, housing closely spaced from and enclosing said coil.

2. The combination of the bearing coil of a directional apparatus, and means to restrict the field of said coil including an element of a housing closely spaced from and enclosing said coil.

3. The combination with a non-directional radio system, of a directional radio system including a rotatable bearing coil electrically symmetrical with respect to said first system, and means to maintain the symmetry between said systems comprising a conductive mass disposed in relatively close space relation to said coil. and geometrically symmetrical about the axis of rotation thereof.

l. The combination with a non-directional radio system, of a directional radio system including a bearing coil, means for effecting electrical symmetry between said systems, and means comprising a conductive mass disposed in close space relation to said coil to maintain said electrical symmetry.

5. The combination of a. directional radio system including a bearing coil, and a ,unidirectional directional system including an element of a housing closely spaced from and enclosing said coil.

6. The combination with a bearing coil, and means for rotating said coil to position related to the direction of a source of electroradiant energy, of a housing therefor comprising two metallic end caps having a circuit relation to said coil, separated by and connected to, a casing of insulating material.

7. The combination of a bearing coil having a natural capacity to the ground or its equivalent, and means to increase said ca pacity including elements of a housing enclosing. said coil and of difi'erent magnitudes of potential.

8. The combination of a bearing coil having a natural capacity to the ground or its equivalent, and means to increase said capacity including an element of a housing enclosing said coil and a connection from said element to the ground or its equivalent.

9. The combination of the bearing coil of a directional apparatus, and means to restrict the field of said coil including elements of a housing closely spaced from and enclosing said coil and of different magnitudes of potential. 1

10. The combination of the bearing coil of a a directional apparatus, and means to restrict the field of said coil comprising two metal caps geometrically symmetrical with respect rical with respect to said first system, and means to maintain the symmetry between said systems comprising an element of a housing closely spaced from and enclosing said coil.

12. The combination with a non-directional radio system, of a directional radio system including a bearing coil electrically symmetrical with r spect to said first system, and means to maintain the symmetry between said systems comprising elements of a housing enclosing said coil and of diiferent magnitudes of potential.

13. The combination with a non-directional radio system, of a directional radio system including a bearing coil electrically symmetrical with respect to said first system, and means to maintain the symmetry between said systems comprising elements of a housing closely spaced from and enclosing said coil, one of said elements being connected to the mid-point of the coil and the other of said elements being connected to the earth.

14. The combination with a non-directional radio system, of a directional radio system including a bearing coil electrically symmetrical with respect to said first system, and means to maintain symmetry between said systems comprising two metal cap members secured to opposite ends of an insulating member to form a closed housing within which said coil is received.

15. The combination with a non-directional radio system, of a directional radio system including a bearing coil electrically symmetrical with respect to said first system, and means to maintain symmetry between said systems comprising two metal cap members secured to opposite ends of an insulating member to form a closed housing within which said coil is received, connected respectively to a mid-point of the coil and to earth or its equivalent.

16. The combination with a non-directional radio system, of a directional radio system including a rotatable bearing coil, means for effecting electrical symmetry between said systems, and means comprising a conductive mass disposed in spaced relation to said coil and geometrically symmetrical with respect thereto to maintain said electrical symmetry as said coil is rotated.

17 The combination with a non-directional radio system, of a directional radio system including a rotatable bearing coil, means for efi'ecting electrical symmetry between said systems, and means comprising conductive masses disposed in spaced relation to opposite sides of said coil and geometrically symmetrical with respect to the axis of rotation thereof to maintain said electrical symmetry during rotation of said coil.

18. The combination of a directional radio system including a bearing coil having an enclosing housing, and a uni-directional directional system including an element of said housing connected to a mid-point of said coil.

19. The combination of a bearing coil rotatable about a vertical axis, a conductive plate spaced from the lower side of said coil extending in a plane substantially at right angles to said axis, a conductive tube symmetrical about said axis and connected to said plate, and conductors to said coil extending through said tube.

20. The combination with a non-directional radio system, of a directional radio system including a bearing coil electrically symmetrical with respect to said first system and rotatable about a vertical axis, and means to maintain the symmetry between said systems comprising metal plates geometrically symmetrical with respect to said axis and oppositely disposed with respect to said coil, a conductive tube connected to one of said plates and symmetrically disposed wit-h respect to said axis, and conductors to said coil extending through said tube.

FREDERICK A. KOLSTER. 

